1. Field of the Invention
The present invention relates to the manipulation of devices through which fluids are delivered to and/or withdrawn from an animal through venipuncture. More particularly, this invention is directed to a holder for use with a fluid collection and/or injection system of the type including a double ended needle assembly and associated fluid container and, specifically, to such a holder having an actuation mechanism for selectively mounting or detaching the needle assembly. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Related Art
While not limited thereto in its utility, the present invention is particularly well suited for use in fluid transfer systems of the type which are used to inject fluids into and to draw blood specimens from a patient. Current medical practice requires that the fluid containers and needle assemblies used in such systems be inexpensive and readily disposable. Consequently, existing blood collection systems, for example, typically employ some form of durable, reusable holder on which detachable and disposable needles and fluid collection tubes may be mounted. A blood collection system of this nature can be assembled prior to use and then disassembled after usage. Thus, these blood collection systems allow repeated use of the relatively expensive holder upon replacement of the relatively inexpensive disposable needle and/or fluid collection tube. In addition to reducing the cost of collecting blood specimens, these blood collection systems also help minimize the production of hazardous medical waste.
The most popular design configuration of previously available blood collection systems includes a double ended needle assembly, an evacuated collection tube, and a holder for maintaining the needle assembly and the collection tube in fixed relation. The double ended needle assembly, which is also referred to as a cannula, has a bore extending therethrough and a hub near a central region thereof. The evacuated fluid collection tube includes a puncturable stopper at one end thereof. In this type of blood collection system, the holder typically has a housing at one end thereof for receiving the needle assembly. Likewise, the holder also has a hollow body with an opening at an opposite end thereof for receiving the collection tube. The needle assembly is rigidly received within the housing of the holder such that a first end of the needle extends forwardly of the holder for puncturing the vein of a patient. The opposite, second end of the needle extends into the hollow body of the holder. Upon assembly of the blood collection system, the needle assembly is inserted into the housing and the collection tube is inserted through the open end of the hollow body until the second end of the needle pierces the puncturable stopper of the collection tube, thereby allowing fluid communication between the interior of the collection tube and the bore which extends through the needle assembly. To draw a blood specimen from a patient using one of these blood collection systems, the evacuated collection tube is partially inserted into one end of the holder, the first end of the needle is inserted into a patient""s vein and the collection tube is fully inserted into the holder such that blood will be drawn through the bore of the needle assembly and into the fluid collection tube. After drawing the specimen, the collection tube is removed so that the blood contained therein can be analyzed and the needle assembly is detached for disposal. In addition to being capable of accommodating blood collection tubes, the holders of some prior art fluid transfer systems are compatible with fluid containers having a fluid to be injected into a patient. Thus, such holders can be used to inject fluid into, as well as draw blood specimens from, a patient. Efforts to improve prior art fluid transfer systems of the type briefly described above have largely focused on improving the mechanism for removably mounting the needle assembly to the holder.
One early, and extremely popular, type of mechanism for removably mounting a needle assembly to a holder utilized a fixed threaded passageway at one end of the holder designed to threadably receive complementary threads on the hub of the needle assembly. With a holder of this type, a threaded cannula could be screwed into position prior to drawing a blood specimen from a patient, subsequently unscrewed from the holder and discarded.
Blood collection systems employing a holder with a fixed threaded passageway, however, suffer from a number of serious deficiencies. The most serious of these deficiencies stems from the need for the health care worker to physically handle the cannula after it has been in contact with the patient""s blood in order to unscrew the threaded cannula from the holder. This handling typically entails placing a protective cap on the externally extending portion of the threaded cannula, twisting the threaded cannula to free it from the fixed threaded passageway of the holder, and disposing of the used cannula. Thus, removal of the needle from a blood collection device of this type inevitably gives rise to the possibility of accidental contact between the health care worker and the patient""s blood. Another deficiency of the above-described arrangement resides in the relatively long period of time it takes a health care worker to remove the needle from the holder. Nonetheless, due to widespread usage of this type of blood collection system, health care workers have now become accustomed to using threaded cannulas.
In response to the above-mentioned deficiencies of fixed threaded passageway holders, holders have recently been developed which employ unthreaded needle-locking mechanisms with a remote release element for ejecting the needle assembly from the needle-locking mechanism. This type of arrangement has generally been considered to be a functional improvement over fixed threaded passageway holders because, by operating the release element, a health care worker may quickly remove a needle assembly from a holder without the need to physically contact any portion of the needle assembly directly. This reduces the risk that the health care worker will accidentally contact the patient""s blood. To date, however, most of the blood collection devices with holders having releasable needle-locking mechanisms have been incompatible with what has now become the industry standard threaded cannula, i.e., a double needle assembly with a threaded hub in a central region thereof and a hub disk located at one end of the threaded portion of the hub. Thus, most of these recently developed holders have required the use of relatively expensive, custom designed needle assemblies.
Holders having a needle ejection feature which are compatible with the standard double needle configuration have also been developed. However, these holders have either suffered from overall poor performance and/or have required the use of a separate adapter, for accommodating a standard threaded cannula, which is discarded along with the cannula upon removal of the cannula from the holder. In addition to increasing the overall cost of the blood collection system, the use of such an adapter can also unnecessarily complicate assembly and/or disassembly of the blood collection system.
In light of the foregoing, there exists a need in the health care industry for a needle holder for use with a fluid transfer system which (1) is compatible with standard threaded cannulas; (2) allows a user to detach a threaded cannula from the holder without physically handling any portion of the threaded cannula; and (3) is capable of operating effectively without the need for any additional components.
The present invention satisfies the above needs, and overcomes the above-stated and other deficiencies of the prior art, by providing a holder having a cannula actuation mechanism within a housing at one end of the holder for removably mounting an externally threaded cannula thereto. The actuation mechanism includes first and second mounting jaws, which may comprise first and second threaded halves with surfaces which cooperate to define a threaded passageway therebetween when the threaded halves are in a cannula-mounting position. At least one of the threaded halves is mounted within the housing in such a manner as to allow movement thereof from the cannula-mounting position to a retracted position wherein the threaded surfaces define a gap which is appreciably greater than the maximum cross-section of the cannula hub. The actuation mechanism also includes an actuator with at least one structural portion for normally maintaining the threaded halves in the cannula-mounting position. The actuator is slidably mounted to the holder and operably associated with the threaded halves such that, upon user-operation of the actuator, at least one of the threaded halves moves to the retracted position. To removably mount a standard double ended cannula to a holder in accordance with the present invention, a user simply inserts a standard threaded cannula, with its protective cap in place, into the holder and screws the threads of the cannula hub into the threaded passageway defined by the threaded surfaces of the threaded halves until the hub disk of the cannula hub abuts the top surfaces of the threaded halves. To release a threaded cannula from a holder in accordance with the present invention, the user simply orients the holder over a xe2x80x9csharps disposal boxxe2x80x9d such that the first end of the cannula extends vertically below the holder, and depresses the actuator to retract the threaded halves thereby allowing the cannula to fall from the holder under the force of gravity.
The cannula holder of the present invention is wholly compatible with standard threaded cannulas. This compatibility is achieved by pivotably mounting at least one of the threaded halves of the actuation mechanism within a housing located at one end of the holder. When these threaded halves are in the cannula-mounting position, a standard threaded cannula can be threaded into the threaded passageway in the same manner as a standard threaded needle assembly would be threaded into a holder having a fixed threaded passageway. However, upon user-operation of an actuator, which is located on the holder in a position where it is unlikely to be contaminated, at least one of the threaded halves pivots apart to a retracted position, thereby detaching the threaded cannula from the actuation mechanism. Thus, the present invention is compatible with standard threaded needle assemblies and can be used by health care workers in a manner substantially similar to the prior art needle holders to which they are accustomed.
Another significant advantage of the present invention when compared to previously available needle holders with an ejection capability is reduced cost. Since the present invention is wholly compatible with both standard threaded cannulas and standard fluid collection tubes, holders in accordance with the present invention do not require the use of expensive custom made cannulas and/or additional custom made components.
Yet another advantage of the invention relative to previously available fluid collection devices is improved reliability and ease of operation. To assemble a fluid transfer device using a holder in accordance with the present invention, a user simply threads a standard cannula into the actuation mechanism at one end of the holder and inserts a fluid container into an opening at the opposite end of the holder. After use, the fluid container is removed from the holder, the holder is positioned over a xe2x80x9csharps disposal boxxe2x80x9d, and the actuator is depressed thereby retracting the threaded halves of the holder and allowing the cannula to fall into the xe2x80x9csharps disposal boxxe2x80x9d under the force of gravity. This assembly procedure is identical to the assembly procedure used with conventional prior art holders. The disassembly procedure, on the other hand, avoids the need to unscrew a cannula, twist a bayonet mechanism or flip a lever as was necessary with various prior art holders.